From: Paul Neubauer
To: All
Subject: "radio-isometric dating" (was: "Re: The Vapor Canopy")
From: 00prneubauer@leo.bsuvc.bsu.edu (Paul Neubauer)
Organization: Ball State U.
In article <1994Feb8.021325.21755@alc-ohio.alc.com>, stassen@alc-ohio.alc.com
(Chris Stassen) writes:
> Brent Paulson writes:
>> 2. What sources of information do you have to prove an old earth?
>> This of course excludes radio-isometric dating. Since it seems
>> that this is always used for reasons for the age of something-
>> suppose that it was incorrect.(It is based on several assumptions.)
> Finally, Brent may be disappointed to hear this... but the reason
> that he finds isotope dates "always used" is that they are really
> about the only means of computing the age of the Earth.
> There are plenty of dating methods which produce relative
> (rather than absolute) ages, and which can be used as checks against
> isotope ages throughout geologic time (for example, one can compare
> the ordering derived from stratigraphic sequence to that derived by
> isotope dating). There are also rough calculations which might
> place lower or upper limits on the Earth's age. But no method (as
> far as I know) other than isotope dating will yield an exact age for
> the Earth.
Chris is, of course, absolutely right that radiometric methods are the
only ones that yield absolute figures for the age of the earth. OTOH,
the age of the earth is not *exactly* what Brent asked about. He
asked about "an old earth" and the data that require it. Since none
of my betters have yet seen fit to ensure that Brent does not
misinterpret Chris's rather circumspect answer to mean that there is
no other evidence for an "old earth," I will throw my $0.02 worth into
the fray. I don't want anyone, such as Brent, to take any comfort
from Chris's statement that only isotope dating can give an actual age
for the earth. :-)
Now, exactly what Brent means by "an old earth" is not yet completely
clear, but most young-earth creationists are looking for ages on the
order of 6,000 to 10,000 years and would certainly be more than a
little distressed if they were forced to admit that the true age
differed by as much as an order of magnitude from that figure. In
practice, virtually no one is willing to consider ages of less than 6k
and even when pressed as hard as Chris Stassen could press, even Bob
Bales tended to say nothing more committed than "probably less than
50k" (approximate quote, I don't have Bob's posts archived like some
people do :-).
Anyway, although we can certainly agree with Chris on the methods
availalble for determining the full age of the earth, there are, as
Chris does note, additional lines of evidence that can place lower
limits on the earth's age. Several of these other, non-radiometric,
methods require ages of considerably more than 6k years. Here are
some of my favorites cribbed shamelessly from my talk.origin archives.
(BTW, some of the material I am quoting from was even originally
posted by Chris Stassen, so I am certainly not accusing him of being
unaware of the data, just of answering Brent's question a little more
narrowly than might be necessary. :-)
1) DENDROCHRONOLOGY.
This is dating from counting tree rings and correlating the patterns
of wide and narrow rings between trees, thus working back farther than
the age of a single individual tree. This methodology does not gain
an order of magnitude, but patterns of tree rings have been traced
back to ages that are at least too old for the Ussher dates. For
example, Becker et al., _Nature_ 353:647-649, 1991 discusses a
sequence of oak trees from Europe that yields a CONTINUOUS chronology
from the present back 9,928 (by now 9930) years.
The same authors also have a 1600 year old pine chronology which
overlaps the end of the oak chronology. As interspecies comparison is
difficult they have not yet fixed an absolute age for the pine
chronology. If they are able to we will probably have a chronology
going back 11,500 years.
The oldest living trees are bristlcone pine trees from the White
Mountains of California/Nevada. The oldest known live ones are
between 4500 and 5000 years old and dead trees have been matched with
live ones, extending the scale of bristlecone pine tree rings of known
age back 7000-9000 years (there seems to be some discrepancy in the
posted sources, but all of the figures are certainly more than 6000
years) before the present. Note, too, that even the ages of the
LIVING trees extend back beyond the usual dates cited (and calculated
from Biblical references) for the purported flood.
Another study, finished in 1984 in Ireland, established an unbroken
record of tree rings in oak trees from the present [i.e., 1984] to
7,272 years ago.
Creationists sometimes object that some trees have been known to form
multiple rings in a single year, but this can be and is controlled
for. I believe there is a FAQ on this topic, but if not, I can repost
some of the informative material that people have posted here on t.o.
in the past.
2) ICE CORES
There is definitely a FAQ on this one. Matt Brinkman has compiled a
beautiful summary of the data. Briefly, though, people have counted
annual layers of ice in places like Greenland and Antarctica.
Naturally, the layers become harder to distinguish as you go deeper in
the ice, but the principles are comparatively simple. It is
comparatively easy to show (e.g., using inclusions of ash from known
volcanic eruptions) that the layers do correspond to years rather than
snowfalls (as Ted Holden has often asserted).
As the ice gets compacted, the layers do become hard to distinguish
and there are various theoretical methods used to test them, so
someone who is inclined to disbelieve in them may feel uncomfortable
accepting figures from beyond the point where people can actually
*see* them reliably. However, even within this more restricted range,
the news is bad for a "young earth." For example, in the Greenland
ice divide (summit) core, it is possible to distinguish 40,000 annual
layers before they grow too thin. Note that in those 40,000 years,
there is no sign of a flood.
Deeper in the core we get to ice laid down in the last interglacial
(circa 120,000 years ago). According to both observations and theory
(Milankovitch) this was a time in which the northern hemisphere was
much warmer than today. Sure enough, at this point the annual layers
reappear. Precipitation was much higher at this time (a consequence
of the greater capacity of air to hold water vapour as temperature
increases) and the annual layers are still 6mm thick despite the
thinning induced by the flow of ice. Roughly another ten thousand
layers can be counted. It is possible, though not yet confirmed, that
more sophisticated isotopic analysis may allow annual layers to be
counted between these two zones, perhaps back to around 70,000 years
before present. This will be quite difficult because these layers
have been considerably thinned by ice flow, and unlike the last
interglacial layers, they were never that thick to begin with.
Very preliminary results on this core were published in Nature,
volume 359, page 311. (Thanks also to Bill Hyde, from whom the last
couple of paragraphs have been stolen. :-)
3) VARVES.
Varves are annual layers of sediment laid down on lake bottoms.
Depending on the climate and environment, you may get different
numbers of layers per year, but in any case they cycle as 2, 3, or 4
distinct types of sediment and then repeat the same cycle again. In
the Green River formation of what is now Wyoming, there are places
with 20,000,000 thin varves, each varve consisting of a thin layer of
fine light sediment and an even thinner layer of finer dark sediment.
According to the conventional geologic interpretation, the layers are
sediments laid down in a complex of ancient freshwater lakes. The
coarser light sediments were laid down during the summer, when
streams poured run-off water into the lake. The fine dark sediments
were laid down in the winter when there was less run-off. (This
process can be observed in modern freshwater lakes.) If this
interpretation is correct, the varves of the Green River formation
must have formed over a period of about twenty million years.
Young-earth creationists insist that the earth is not much more than
10,000 years old and that the geologic strata were laid down by the
Flood. Whitcomb and Morris therefore attempt to attribute the Green
River varves to "a complex of shallow turbidity currents..." (p.
427). Turbidity currents--flows of mud-laden water--generally occur
in the ocean, resulting from underwater landslides. If the Green
River shales were laid down during the Flood, there must have been
forty million turbidity currents, alternatively light and dark, over
about three hundred days. A simple calculation (which Creationists
have avoided for twenty years) shows that the layers must have formed
at the rate of about three layers every two seconds. A sequence of
forty million turbidity currents covering tens of thousands of square
miles every two-thirds of a second seems ridiculously unlikely.
4) CORAL CLOCKS.
Short explanation: the moon is slowly sapping the earth's rotational
energy. The earth should have rotated more quickly in the distant past,
meaning that a day would have been less than 24 hours, and there would
have been more days per year.
There is an exceedingly strong correlation between the "supposed age"
of a wide range of fossils (corals, stromatolites, and a few others --
collected from geologic formations throughout the column and from
locations all over the world) and the number of days per year that
their growth pattern shows.
Modern corals deposit a single, very thin layer of lime once a day.
It is possible with some difficulty, to count these diurnal
(day-night) growth lines and to determine how old the coral is in
days. More important seasonal fluctuations will cause the growth
lines to change their spacing yearly so that annual increments can
also be recognized much as in growth rings of trees. Professor John
Wells of Cornell University began looking for diurnal lines of fossil
corals. He found several Devonian and Pennsylvanian corals that do
show both annual and daily growth patterns. He found that the
Pennsylvanian forms had an average of 387 daily growth lines per year
cycles, and that the Devonian corals had about 400 growth lines.
The agreement between these clocks, and radiometric dating, and the
theory of superposition is a little hard to explain away as the
result of a number of unlucky coincidences in a 300-day-long flood.
[The above excerpts, somewhat edited by me, were posted to
talk.origins over the past several years by a number of people, some
of whom I can't even identify from my files. :-( Chris Stassen, Matt
Brinkman, Bill Hyde, Karl Kluge and Bill Jefferys are certainly among
them, though.]
What these various data show is that there is a good deal more than
radiometric data available to establish that the earth is much more
than 6,000 years old. Anyone trying to build a history of the earth
from the chronology given in Genesis will have a lot of trouble with
any of these, let alone all of them. The correlations between these
methods and the radiometric methods is much too high to be dismissed
as coincidental (despite Bob Bales).
--
Paul Neubauer 00prneubauer@bsuvc.bsu.edu 00prneubauer@bsuvax1.BITNET
pneubaue@bsu.edu neubauer@bsu-cs.bsu.edu
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